Wyers: Why we need replacement level

From SABR member Colin Wyers at Baseball Prospectus on September 11, 2013:

Last week, we talked about different ways to measure offensive performance. Let’s talk some about baselines. The past few weeks have had a lot of math; this time I want to step back and talk some theory (although we’ll have a fair amount of math as well.)

What’s funny is that sabermetrics is regarded as being about math first, when really the heart of the thing is theory. I and my fellow travelers have been accused of “ruining” the game with numbers. But from its earliest days, the spread of baseball was as much about newsprint filled with columns of numbers in agate type as it was about the stories written about the game. Numbers have always had an incredible power to tell us about the game of baseball, and that was as true in 1913 as it is in 2013. Scratch any columnist who talks about how stats are ruining the game and you can find a voluminous knowledge of the history of the game as told in numbers, of the records people hold and the records people haven’t managed to break.

But the relationship baseball fans, writers, and front office personnel have with numbers is changing. Traditional baseball stats are, by and large, an accounting of what happened on a baseball field. At their best, they count the fundamental events on the field—walks, strikeouts, home runs, etc. At their worst, you have convoluted and frankly biased counts of things— runs batted in, earned or unearned runs, games “saved.” Modern stats, by contrast, attempt to relate what happened to the fundamental building blocks of baseball, runs and wins.

So in general, with traditional baseball stats, you’re evaluated by either having lots of the things that are considered good, or fewer of the things that are considered bad. The statistics that have been inspired by sabermetrics, on the other hand, have largely been about evaluating a player inside of a context. What this means is that sabermetrics tends to evaluate things in marginal or relative terms, rather than in absolute terms.